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Read Contract Method

Checking the state of a contract and verifying it.
Most quests verify by reading on-chain data and checking conditions.

- Curve Pool Quest

At first, we obtain liquidity pools using the following method:
  • Pool List from documentation
  • Retrieve meta pool info from meta pool factory contract
async function getFromMetaPoolFactory() {
const provider = new ethers.providers.JsonRpcProvider(process.env.RPC_MAINNET);
const metapool = new ethers.Contract("0xB9fC157394Af804a3578134A6585C0dc9cc990d4", abi, provider);
const addresses: Array<string> = [];
const numPools = await metapool.pool_count();
for (let i = 0; i < numPools; ++i) {
const addr = await metapool.pool_list(i);
console.log(`got metapool address ${addr}`);
addresses.push(addr.toLowerCase());
}
return addresses;
}
  • Get V2 pool
    • trycrypto2:
      0xd51a44d3fae010294c616388b506acda1bfaae46
    • crveth:
      0x8301AE4fc9c624d1D396cbDAa1ed877821D7C511

Next, we check users tx history

  1. 1.
    Retrieve the transaction data (txdata) for the address. We can do this using an API such as EtherscanAPI or a blockchain explorer tool.
  2. 2.
    Inspect the txdata to see if any of the transactions include calls to the desired function.
  3. 3.
    If you find a transaction that includes a call to the function, we can verify that it was executed.
export const txFilter_22: EtherscanFilter = (tx: EtherscanTxItem) => {
// check tx target is a curve pool
if (deps.curvePools[tx.to] && tx.isError === "0") {
// check tx function name
const functionName: string = tx.functionName.split("(")[0];
if (functionName === "add_liquidity") {
return true;
}
}
return false;
};
const txs = await getEtherScanTx('homestead', address, etherscanApiKey)
let count = 0
txs.data.every((tx: EtherscanTxItem) => {
if (txFilter_22(tx)) { ++count; }
if (count >= value) {
// break the loop
return false
}
return true
})
if (count >= value) {
return [true, count]
}
else {
return [false, count]
}
Finally, if user get true result, they can mint curve pool object.
Curve Pool Object

- DAI Holding Quest

In this case, we can check contract's read method is used to verify the balance of DAI.
We verify whether an address has a sufficient balance.
const DAI = new ethers.Contract(DAI_ADDRESS, ERC20ABI, provider);
DAIBalance = await DAI.balanceOf(useraddress);
Balance is easy to check. You can check DAI contract read method.
Dai Etherscan